Wei Mun graduated from the University of Canterbury, New Zealand with a Bachelor of Laws degree and was called to the New Zealand Bar as a Barrister and Solicitor of the High Court of New Zealand in 1985. He was admitted as an Advocate and Solicitor of the High Court of Malaya in 1986 whereupon he joined the Firm and was admitted into partnership on January 1, 1991. At present, Wei Mun principally practises in the field of construction law. His practice includes all forms of dispute resolution in respect of the construction industry particularly in the field of arbitration and litigation. Over the years, more than 20 of his cases have been reported in the law journals.

Wei Mun is also involved in advisory work and the drafting of construction and other related contracts. He is a member of the Panel of Arbitrators for the International Chamber of Commerce, Malaysia and a member of the First Panel of Arbitrators for the Kuala Lumpur Regional Centre for Arbitration. He is also a Fellow of the Chartered Institute of Arbitrators, a Fellow of the Malaysian Institute of Arbitrators, a Fellow of the Singapore Institute of Arbitrators and a Registered Mediator with the Malaysian Mediation Centre.